- Add app/package category browsing via AppStream + comps groups
(lib/category_service.dart), with per-package tag chips shown when a
package is selected.
- Add a Settings page to uninstall PackageKit if it's no longer wanted.
- Rename the app from "Package Launcher"/pkg_launcher to "DNF Package
Store" across the pubspec, window title, and Linux CMake/runner config.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>